Heat the oil in a pot over medium high heat. Add the onions and salt and cook for a few minutes. Add the mushrooms, pepper, chilli powder and paprika. Stir occasionally until mushrooms soften. Add walnuts and cook for a few minutes. Stir in lentils, ketchup, tomato paste, hot sauce and liquid smoke until lentils are heated through, about 5 minutes. Adjust seasoning as needed.
Toast buns and top with super generous amount of sloppy joe mix!